JPH0115848Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates to an engine oil monitor that measures the temperature of engine oil while the engine is running and detects the oil level after the engine is stopped.

〓Conventional technology〓 Conventionally, an engine oil low warning system detects the change in resistance value due to the difference in temperature rise between the thermistor oil and air, and notifies you when the engine oil level falls below a specified level. The device is known.

Figure 3 shows an example of the oil level detection circuit, which was developed by the applicant and has already been filed with the Japan Patent Office (Utility Application No. 59-48531 (Utility Model Application No. 59-48531). 162210)).

The operation will be briefly explained.

Of the two timers IC1 and IC2, the former has a longer operating time (for example, IC1 has a longer operating time).
10 minutes, IC2 5 minutes), now when the ignition switch SW is turned off, the 2-circuit relay RL2 is de-energized, and the mimer starting relay RL1 is energized for a short time (determined by capacitor C and resistor R1). 2 timers IC1 and IC2
starts, and after a predetermined period of time (around the time the engine oil falls into the oil pan), the operation of timer IC2 ends, transistor T1 becomes conductive, and power is connected to the series circuit of resistor R2 and thermistor N, and comparison circuit IC3. be done.

When the engine oil is less than the specified amount, an H level signal is output to the output terminal of comparison circuit IC3, turning on thyristor Th, and then the operation of timer IC1 ends and self-holding relay RL3
Since the thyristor Th remains on even after the oil is turned off, when the ignition switch SW is closed the next time the engine is started, the switching transistor T2 becomes conductive and the light emitting diode D1 lights up to indicate the lack of oil. It's becoming like that.

Note that the circuit consisting of PUT and transistor T3 will cause the light-emitting diode D to open when the thermistor N is disconnected.
This is to issue an alarm by flashing 1.
Further, the light emitting diode D2 is for displaying operation.

〓Problems to be solved by the invention〓 However, such low engine oil warning devices only operate for a few minutes after the engine is stopped, and have no function while the engine is running.
It was necessary to provide a separate oil temperature measuring device to measure the temperature of the engine oil.

The object of this invention is to provide an engine oil monitor that measures the temperature of engine oil during engine operation using the thermistor element of the conventional device.

<Means for Solving the Problem> In order to achieve the above object, the engine oil monitor of this application includes a timer starting circuit that starts a timer when the ignition switch is turned off, and a timer starting circuit that starts a timer when the ignition switch is turned off, and a timer starting circuit that starts a timer when the ignition switch is turned off. An oil level detection circuit that measures the resistance value of a thermistor installed at a predetermined level position in the engine after a predetermined period of time and detects that the engine oil has decreased below the predetermined level, and an ignition switch are installed. The oil temperature measuring circuit measures the resistance value of the thermistor to measure the temperature of the engine oil, and the oil temperature measuring circuit operates while the engine is running, and the oil level detecting circuit operates after the engine is stopped.

〓Operation〓 When the ignition switch is on, the oil temperature measurement circuit operates and measures the temperature of the engine oil, and when the ignition switch is turned off, the timer starts and detects the oil level when a predetermined period of time has elapsed. A circuit operates to detect whether the oil level is at a specified level.

〓Example〓 A first example of this invention will be described with reference to FIG.

The differences from the conventional device shown in Figure 3 are as follows.
The point is that an oil temperature measuring circuit surrounded by a dotted line is added between the hot terminal of thermistor N and the ignition switch SW.

The oil temperature measuring circuit includes a resistor R4 that supplies a minute current to the thermistor N via a diode D3, voltage dividing resistors R5 and R6, and an oil temperature measuring circuit connected between opposing connection points of a bridge circuit constituted by these elements. It consists of a thermometer (ammeter) M.

When the ignition switch SW is closed (that is, when the engine is running), a small current that does not cause self-heating is supplied to the thermistor N through the resistor R4 and diode D3, and the thermistor N The resistance value changes, which changes the current flowing to the oil temperature gauge M, and the temperature of the engine oil is measured and displayed.

When the ignition switch SW is turned off, the power supply to the oil temperature measuring circuit is cut off, so its operation stops.In its place, the oil level detecting circuit starts and operates in exactly the same way as the conventional device.

At this time, since the diode D3 is connected, there is no risk that current will flow to the oil temperature measuring circuit and cause malfunction or damage the oil temperature gauge M.

FIG. 2 shows the oil temperature measuring circuit of the second embodiment, and other omitted parts are the first and second embodiments.
This is exactly the same as the embodiment.

The oil temperature gauge (voltmeter) M is designed to supply a minute current to the resistor R7 and the thermistor N via a constant voltage circuit, and is connected between both terminals of the resistor R7.
The resistance value of the thermistor N, that is, the temperature of the engine oil is measured and displayed.

Its operation is exactly the same as the first embodiment.

Effects of the invention As explained above, the engine oil monitor of this invention includes a timer starting circuit that starts the timer when the ignition switch is turned off.
an oil level detection circuit that is controlled by the timer and measures the resistance value of a thermistor installed at a predetermined level position in the engine when a predetermined time has elapsed after the timer starts, and detects that engine oil has decreased below the predetermined level; The oil temperature measuring circuit measures the resistance value of the thermistor to measure the temperature of the engine oil when the engine is turned on, and the oil temperature measuring circuit operates while the engine is running, and the oil level detecting circuit operates after the engine is stopped. By simply adding a simple oil temperature measurement circuit to the oil level detection circuit of the conventional device, the temperature of the engine oil can be measured when the engine is running using a thermistor element for oil level detection. It is something that can be done.

[Brief explanation of the drawing]

Figure 1...Circuit diagram of the engine oil monitor of the first embodiment of this invention, Figure 2...Circuit diagram of the oil temperature measuring circuit of the second embodiment, Figure 3...Conventionally known engine oil reduction Circuit diagram of the warning device. IC1, IC2...timer, IC3...comparison circuit,
N...Thermistor, NC...Normally closed contact, NO...
Normally open contact, RL1...Timer starting relay, RL
2...Two-circuit relay, RL3...Self-holding relay, SW...Ignition switch.

Claims (1)

[Scope of utility model registration request] There is a timer starting circuit that starts a timer when the ignition switch is turned off, and a timer starting circuit that is controlled by the timer and measures the resistance value of a thermistor installed at a predetermined level position in the engine when a predetermined time has elapsed after the timer starts. The oil level detecting circuit detects that the oil level has decreased below the predetermined level, and the oil temperature measuring circuit measures the resistance value of the thermistor to measure the temperature of the engine oil when the ignition switch is turned on. This engine oil monitor features an oil temperature measurement circuit that operates inside, and an oil level detection circuit that operates after the engine is stopped.